1. Field of The Invention
Applicant's invention relates to measurement devices, and more specifically to measurement devices useful in determining the size and thread spacing of threaded orifices.
2. Background Information
A common problem with respect to vehicle and heavy equipment maintenance relates to using appropriate oil filters when changing engine oil, transmission fluids, hydraulic fluids and related lubricating or force transmission fluids. While it may seem that merely providing to the filter supplier the stock number of the filter already on the equipment, or referring to some technical manual would provide the information necessary to always insure proper filter replacement, such is quite often not the case. Oil filters are by necessity in locations on most engines where they accumulate dirt and grime which obscure the part or model number, and/or are often exposed to conditions which abrade or otherwise lead to the removal of the painted characters or label which indicates the model or part number. This problem is exacerbated by the frequent lack of technical manual references for older or less common vehicles or equipment. Further still, even if the owner of the vehicle or equipment has the appropriate model or part number for the intended filter, the supplier may not have the filter in stock, and an alternative may be needed.
Some or all of the above-described circumstances will necessitate a determination of appropriate filter size solely by reference to the existing filter. One critical aspect of this determination, and one which proves quite difficult by mere visual inspection, is determining the diameter and thread distribution of any spin-on filter's threaded intake orifice. Choosing precisely the correct diameter and thread distribution for a spin-on filter is absolutely crucial. Even a slight variation from the proper specification may result in an imperfect seal between the filter and the equipment, with a loss in oil leading to potential catastrophic mechanical failure. Also, a mis-match of thread sizes may "strip" the threads of the filter stud on the equipment's filter manifold which, in turn, will require costly repairs and delay in further use of the vehicle or equipment.
Part of the difficulty in determining the diameter of the intake orifice of an oil filter lies in the fact that the diameter is not that which may be seen through mere visual inspection. This is true because the reported intake orifice diameter of an oil or other spin-on filter is the distance between diametrically opposed points on thread trough bottoms, not the more easily observed distance between opposite thread crests.
Another obstacle to correct assessment of oil filter specifications lies in the subtle differences between differing thread distributions, differences which incrementally vary in mere hundredths of inches in relative spacing of threads.
A need exists for means by which one can reliably determine the orifice diameter and thread distribution of the intake orifice of any spin-on filter in the absence of which are created circumstances leading, at worse, to equipment and vehicle maintenance problems, and, at least, to time consuming investigations for properly fitting replacement filters.